1. Field of the Invention
The present invention generally relates to a signal processing device, signal processing method, and program, and in particular relates to a signal processing device, signal processing method, and program for gradation expression in video signals.
2. Description of the Related Art
Gradation in a video signal is originally smooth, having an infinite number of gradation steps. However, a digital video signal, which is a quantized video signal, has a gradation rounded off to a finite number of gradation steps, such as 256 gradation steps expressed by eight bits, for example. The digital video signal is therefore incapable of expressing the gradation of the original video signal. Various techniques have been proposed to make the gradation expression in the digital video signal as close to the original video signal as possible.
Related techniques include, for example, a frame rate control (FRC) method that expresses intermediate gradation steps utilizing the integration effect of visual perceptions in the time direction by changing the gradation frame by frame, as well as techniques for expressing intermediate gradation steps utilizing the spatial integration effect of visual perceptions by changing the gradation pixel by pixel, such as error diffusion, super bit mapping (SBM), and dithering. As disclosed in Japanese Unexamined Patent Application Publication Nos. 2006-221060 and 2009-207113, for example, these techniques are being improved.
On the other hand, as disclosed in Japanese Unexamined Patent Application Publication No. 2009-151151, for example, provision of stereoscopic video is becoming common in recent years. The stereoscopic video is provided by showing video images shifted by the amount of parallax to the right and left eyes of the viewer so that the viewer perceives a single three dimensional video image. The above problem of gradation expression also occurs in the provision of stereoscopic video as long as the video images shown to the right and left eyes are formed from digital video signals.